Current methods for treating or processing animal substrates such as skins, hides, pelts, and leather can necessitate the use of vast quantities of water. For example, in treatment methods wherein the animal substrate comprises a hide, typically 30 kg of water is required per kg of hide. Large volumes of water can be needed in order to remove unwanted materials from the animal substrate (such as those that are liable to decomposition) and in subsequent steps of the process which involve chemical modification to confer certain properties on the animal substrate. Chemical modification of the substrate can be carried out for the purpose of, inter alia, preserving, waterproofing, colouring and/or providing any desired textural or aesthetic qualities. The various steps described above will generally be performed in the presence of a treatment formulation comprising one or more components.
Due to the large quantity of water relative to the weight of animal substrate, current treatment processes known in the art require a commensurate increase in the amount of chemicals used in the treatment formulation to ensure an effective treatment of the substrate within an acceptable timeframe. Consequently, excessive amounts of polluting and environmentally damaging effluents are produced from such processes. Furthermore, because only low levels of mechanical action can be used to avoid damaging the animal substrate, long process times are necessary.
Many of the methods for preparing animal substrates for human use still remain predominantly based on traditional processes and there have been few advances in recent years. For example, methods for the processing and manufacturing of leather have remained largely unchanged for 75 years. EP0439108 filed in 1991 and directed to a process using carbon dioxide for deliming of hides, discloses an example of one of the few recent developments in this field.
Prior to the development of the method disclosed herein, the inventors have previously addressed the problem of reducing water consumption in a domestic or industrial cleaning method. Thus, in WO-A-2007/128962 there is disclosed a method and formulation for cleaning a soiled substrate, the method comprising the treatment of the moistened substrate with a formulation comprising a multiplicity of polymeric particles, wherein the formulation is free of organic solvents. However, although the process disclosed therein relates to an improved means for cleaning a soiled substrate requiring less water, the application does not disclose a method or process for treating an animal substrate.
There is therefore needed an improved method for treating or preparing an animal substrate by tanning and/or by one or more associated tannery processes which ameliorates or overcomes the above-noted problems associated with the methods of the prior art. Particularly, there is needed such a method for treating an animal substrate which requires less water than the methods of the prior art and that reduces the volume of polluting and hazardous effluent produced from such a method. Furthermore, there is a desired such a method for treating an animal substrate which is faster, more efficient and provides a substrate with improved properties when compared with methods of the prior art. Still further there is a need for such a method of treating an animal substrate which provides a substrate with one or more of the following properties:
i. Deeper penetration of components of the treatment formulation into the animal substrate;
ii. More uniform treatment of the surface of the animal substrate;
iii. Improved fixation of the treatment formulation components into the animal substrate;
iv. Improved surface aesthetics including feel and appearance;
v. Improved resistance of the treated animal substrate to shrinkage;
vi. Reduced creasing and/or mechanical damage to the animal substrate;
vii. Improved longevity of the final treated substrate.